Ground Works: Drains and Foundations

After a three week break over Christmas and New Year, the build was back in action.  It is cold, wet and mucky.  And the guys just workedthrough it.

The existing drains ran horizontally through the new foundations, which the structural engineer said is a big no.  So the guys dug some trenches and rerouted the drains, including a lintel in the foundation bricks.  This was the last bit of the outer foundations that had to be poured before the bricks could be laid.

Foundations

The foundation brickwork took a day and a half, for two experienced bricklayers.  It's a double course, the interior will have the timber frame, and the exterior will have the (Building Control required) external block work.

The bricks were laid right on top of the cement that had been poured, which is hard to tell from the picture because it's so muddy.

This picture doesn't really show much either at first glance.  Except that the soil behind the wall is ground level.  The brick wall is on top of the concrete foundation, and the soil in front has already been mostly excavated.

Once the foundation brickwork was completed, the guys used a micro digger to excavate the solum.  It was about 20 cm (8 inches) in some places, 10 cm (4 inches) in others since our plot is on a slope.  You can see at the front wall they left an opening for the micro digger to exit.

And look!  The ground is prepped for the concrete slab to be laid.  (View to the rear of the extension)

They put in about seven tons of hardcore, compacting it every now and then.  Then sand, a damp proof membrane and insulation.  (View to the front of the extension.)  

The put steel on top of the insulation, and then because of the weather, it stayed like that for a week.

Last Friday (January 22, 2016...a day to remember because it was such nice weather) it finally was warm enough for the concrete to get poured.  They barrelled it in, one wheelbarrow after another.

And when they were done, we had a concrete slab.  We are out of the ground!  (View to the front of the extension.)

It looks like it's going to be another three weeks (mid February?) before the joiners will be on site to do the timber kit.  In the meantime, the concrete pad is supposedly curing.  It's seems to be turning into a swimming pool, with all the rain.  And the cat managed to leave his mark.

Drainage

Once the brick foundations were laid and the solum was excavated, the guys dug a trench for the access hatch.  This way, if there is any blockage down the line (please, no!!) then at least we have a straight line to clear the blockage.

Pipes placed, access chamber in situ, and the trench is filled in with the excavated soil.  I wasn't able to get photos of some of the drainage before it got buried, so I hope to get some from the builders in case Building Control asks.

We'll have a gutter and down pipe on the end of the extension, so they built that into the new drains as well.

The ground works to this point cost about £10K, around a quarter cost of the entire build budget.  Once the timber kit goes up, the extension will take shape!